AR Barrel Question

[MudCamper]

Why do my AR barrels have what looks like sloppy weld slag on the muzzle, on the ones with brakes or flash hiders? Is this just lazy/sloppy manufacturing or does it serve some purpose?

And, can I grind/chip it off? I have a new Stag upper/barrel that part of it broke/blasted off by itself within the first 100 rounds.

[ar15barrels]

Why do my AR barrels have what looks like sloppy weld slag on the muzzle, on the ones with brakes or flash hiders? Is this just lazy/sloppy manufacturing or does it serve some purpose?

And, can I grind/chip it off? I have a new Stag upper/barrel that part of it broke/blasted off by itself within the first 100 rounds.

That's either chrome lining or carbon buildup.
You can scrape off carbon buildup, but don't damage the crown.
Don't try to scrape off chrome lining.

[MudCamper]

Well it sounds like what I am refering to is the crown then. And part of it basically just fell off. I will take a pic later and post it.

[MudCamper]

OK here's a pic of the muzzle:



This is a brand new Stag, shown with a thread protector on it. Notice that the upper left quarter of the "crowning" is missing. It was not that way when I first got it. I noticed this after I had fired 120 rounds through it.

This is the same upper that I have all kinds of other problems with.

[ar15barrels]

This is a brand new Stag, shown with a thread protector on it.
Notice that the upper left quarter of the "crowning" is missing.
It was not that way when I first got it.
I noticed this after I had fired 120 rounds through it.

That "slag" is carbon buildup.
The area where it's missing is your actual muzzle.
Use a brass or aluminum scraper to knock the carbon off.

That upper did not always have that thread protector on it.
You only get buildup like that when you have a muzzle device on it that captures the carbon.

That's a LOT of carbon for only 120 rounds.
I suspect there are either more rounds through it, or you are shooting some crappy ammo that makes a lot of carbon buildup.

[apbrian112]

i was gonna say the same thing... that does look like a lot of carbon for only 120 rds...

[MudCamper]

I bought the upper/barrel brand new with that "build-up" on it. WTF?

(And I put the thread protector on it.)

[ar15barrels]

I bought the upper/barrel brand new with that "build-up" on it. WTF?

I hate to break it to you, but the barrel was certainly NOT new when you bought it if it had that buildup.
I would estimate that carbon buildup is from about 500 rounds fired and there was certainly a muzzle device on there when those rounds were fired.

Who did you buy it from?

[AJAX22]

I buy alot of used AR parts, some better than others, And i've never picked up anything that had that much carbon on it.

Heck even my beater guns that I run wolf ammo through don't get carbon on them like that (and I have linear compensators on some of them)

I'd say if anything Randal's understating how used that looks.

Methinks you've been rooked.

[ar15barrels]

I'd say if anything Randal's understating how used that looks.

I was going to say 500-1000 rounds at first, but I really don't know for sure so I estimate on the low end as to not hurt his feelings as much.
I have seen barrels with 5K rounds fired without ever removing the muzzle device and they had
over 1/16" of carbon built-up in there, filling ALL the space between the muzzle and the inside of the muzzle device.

I took a picture of that, but I don't know where it is right now.

[MudCamper]

Yep. Carbon. I just spent the last hour with a brass brush and I still only got 80% of it off.

I bought this upper assembly with barrel new from Wes at Ten Percent. Now Wes is a great guy so all I can think is that Stag put a used barrel on a new upper. But based on how crappy the upper has performed (see my first and earlier posts) maybe the entire thing was a return that they resold. This was the second one Wes sent me, because the first one was a 3L with 3H tags on it in a 3H box.

At the very least, Stag better give me a new one. Better, I want to return it for a refund. My taste for Stag has been totally soured at this point.

[jandmtv]

guys this is a bit off topic, but whats the best way of getting rust out of a non chrome lined barrel? (mosin nagant m91/30) i noticed a little rust in the rifling on my mosin and wana know what chemical i should use, would wd40 do the trick? i have some birchwood casey blue and rust remover, but im affraid it will harm the blueing too. any thoughts?

EDIT: how about using CLR (calcium lime rust remover) from home depot with a bore brush, will this work?

[ar15barrels]

I bought this upper assembly with barrel new from Wes at Ten Percent.

Ouch.
I think I know the upper you bought.

There was one that Wes mentioned running a bunch of rounds through it.
I made a funny comment not to buy a Stag from him for a couple days until he sold it.

[jandmtv]

no one has advice on the rust cleaning?

[ar15barrels]

no one has advice on the rust cleaning?

I recommend keeping your rust away from your firearms.